Agree chuffin if someone I was not already friends with started texting and calling me about random stuff all the time I would think they fancied me.
I have a great male friend of many years standing. We have a wonderful rapport and when we get together it's as if the rest of the world disappears sometimes.
His partner used to find me threatening, not to their relationship (they're gay, I was de facto not a threat) but he didn't like that when we met up he felt like he barely existed. This was both of our faults, but when I found out about it I asked my (now) DH whether it was true, and he said that yes, when my friend and I got together we were so wrapped up in each other that we kind of left other people out.
This was totally, absolutely neither intended, nor realised. I adored my friend's partner, but my friend and I rarely saw each other and I guess when we did we got carried away with catching up and teasing and arguing and joking together.
Since I realised the effect I was having I have been much more conscious of not making his partner feel excluded. DH never felt excluded in the same way. He's a different kind of person, less sensitive to that kind of thing and he just found us ridiculous and funny when we were together.
So I could well have ended up having a strained relationship with my friend's partner, could have resented him his "jealousy" and allowed our relationship to deteriorate. But instead I paid attention to the ways I was behaving that were making him uncomfortable and addressed them. Now they are both my friends.
But I think couple relationships do matter, even ones you're not in. It matters to me that I get along with the spouses and partners of my friends.